McKinney, TX Accessory Structures: ADU Impact Fees (2026)

McKinney does not offer ADU-specific impact fee waivers. Standard development fees apply: building permit fees based on construction valuation under the McKinney Building Inspections fee schedule, plan-check fees, and trade permit fees (electrical, plumbing, mechanical). McKinney collects water and wastewater impact fees under Texas Local Government Code Chapter 395 (Impact Fee Act) and the City's adopted Land Use Assumptions and Capital Improvements Plan — current rates per single-family equivalent typically run in the low thousands per category (water, wastewater, roadway) and are subject to periodic update by City Council ordinance. Roadway impact fees apply in adopted roadway service areas across McKinney. Where the accessory unit shares the principal dwelling's existing water/sewer tap and meter, most impact fees can be avoided — McKinney's Engineering and Public Works staff strongly encourage this approach for accessory structures. Oncor handles electric service; Atmos Energy supplies natural gas; service-extension fees apply separately. Texas has no statewide ADU impact-fee waiver analogous to California Gov. Code §65852.2(f). Property taxes will adjust through the Collin Central Appraisal District's annual reassessment, which covers McKinney ISD, Collin County, Collin College, and the City of McKinney levies.